Electronic systems, devices and applications are continually developing. From cellular phones, portable computers, and compact fuel-cell based generators, to electrical vehicles, the list of electronic systems, devices and applications seems endless. As the number of systems and devices continues to increase, and the applications in which they are used continue to grow, the demand for efficient energy/power supplies that are able to power these systems and devices over extended periods of time has also increased. More specifically, as high performance electronic systems and devices with high power consumption are introduced rapidly to the market place and/or as natural resource scarcity gradually intensifies and the cost of energy consequently increases, the ability to efficiently provide and utilize power is ever increasing.
FIG. 1 illustrates a conventional drive system 113 for providing power to drive a load. The load may be any type of known electronic system or device such as a graphics display, a microprocessor, a memory, a conventional laptop computer or an electric motor. The drive system includes an energy or power source 109 (such as a battery, a fuel cell, a solar cell, etc.) for driving the load 112. The system further includes a regulator/converter 108, and may further include current control elements 110 and 115, which may also be omitted. Here it is noted that 108 may be a regulator and/or a converter, and each may be used interchangeably as they are equivalent in the context of this document. A regulator maintains its output constant within a specified range regardless of changes to its output loading condition, shifts in environment condition (such as temperature, humidity, etc.), or/and variations in its input level. A converter is a known electrical element that takes an input parameter, such as a voltage and produces a prescribed output parameter(s), such as a desired voltage at the output. For example, in a case where the desired conversion is from a low input voltage to a higher output voltage, a step up (boost) voltage converter can be used to achieve the desired output voltage. Alternatively, in the case where the desired conversion is from a high input voltage to a lower output voltage, a step down (buck) voltage converter can be used to achieve the desired output voltage.
Current control elements 110 and 115 are optional elements and are preferably set to control the amount of current provided to the load 112. Examples of elements that can be used as a current control element are a diode, field-effect transistors (MOS FET, JFET, etc.), a bipolar transistor, an insulated gate bipolar transistor, a silicon controlled rectifier, and/or a relay switch. One or more of these elements can be connected in series and/or parallel to act as a current control element and placed in any electrical path(s) within the system.
One problem with this system is that as the load increases in complexity and functionality, the amount of power required for driving the load increases. While conventional power/energy supplies, such as disposable and/or rechargeable batteries are always improving in order to extend the length of the battery life, recent advances in high capacity batteries has not resulted in considerably longer battery life because the increase in power consumption of these electronic systems and devices more than offsets the improvement in battery life.
U.S. Pat. No. 6,570,632 issued to Estes, et al. (hereinafter referred to as “the Estes patent”) proposes one solution for extending the life of a rechargeable battery used to charge/power a portable system—such as a cellular phone. The Estes patent teaches using heat generated by at least one electrical component which is resident on a printed circuit board (PCB) within the system, and converting this heat into electrical energy. The Estes patent further teaches using this electrical energy to directly recharge the main power source—a rechargeable battery.
There are several disadvantages to the solution proposed by the Estes patent. First, the Estes patent uses the electrical energy to directly recharge a main energy/power source—the rechargeable battery—such as a lithium-ion battery—which can only be accomplished through carefully controlling a complex electrochemical process. Thus, the Estes patent requires that the main power source be a rechargeable battery and further requires complex battery charging, conditioning and maintenance system circuitry, which must be built into the system. Second, using the electrical energy to recharge the main power source can be inefficient in situations where the system is in use and the main power source must continue to provide energy/power to the load. Accordingly, recharging of the battery would likely occur optimally at a time when the system is not in use and is not taxing or drawing charge from the battery; however, at such time the electrical device(s) in the system is not likely to generate much heat. Therefore, the Estes patent does not make optimal use of the heat generated by the system when it is active. Finally, rechargeable batteries lose their charging/storage efficiency over time as they are repeatedly charged-discharged and/or continually used. Accordingly, in the solution proposed by the Estes patent, the efficiency and longevity of the life of the main power source—the rechargeable battery—may actually be decreased and system may become less efficient if the system is continually attempting to recharge the battery whenever it is turned on.
Therefore, there exist needs in the art for a system and method that extends the life of a main power source and provides for more efficient power use without requiring significant additional complex circuitry. There further exists a need for such a system to be able to be implemented in situations where the main power source may not be a rechargeable battery. There further exists a need for such a system where heat generated by the system may be efficiently converted into electrical energy at optimal times and stored for future use, thereby improving the efficiency of such a system.